Signed in as:
filler@godaddy.com
AUTO Application 1UZ-FE Wiring
AUTO Application 1UZ-FE Wiring – Service Discontinued
AUTO Application 1UZ-FE Wiring – Service Discontinued
🚨 IMPORTANT NOTICE: We have officially discontinued our standalone wiring service for the 1UZ-FE non-VVT engine in automatic applications.
Why We No Longer Support the 1UZ-FE Non-VVT
This decision has been made to protect our customers from making a bad investment by using an outdated engine platform that no longer meets modern performance, reliability, and diagnostic standards. While the 1UZ-FE non-VVT was a groundbreaking engine in its time, it has now been surpassed by newer, more efficient, and more tunable options.
Key Issues with the 1UZ-FE Non-VVT
🔴 Aging ECUs & Reliability Problems – Many original ECUs now require rebuilding, which can lead to unexpected costs. We do not offer ECU rebuilding, and even professional rebuilders cannot guarantee that a rebuilt ECU will function correctly.
🔴 Outdated Ignition System – The distributor-based ignition system with plug leads is less reliable than modern coil-on-plug (COP) systems, which offer better performance, reliability, and tuning flexibility.
🔴 Lack of VVT-i – Without Variable Valve Timing (VVT-i), the non-VVT 1UZ-FE has:
- Lower torque at low RPMs
- Worse fuel efficiency
- Reduced overall tuning flexibility
🔴 Idle Control Valve Issues – The idle control valve is prone to failure, often sticking or malfunctioning, making it difficult to maintain a stable idle.
🔴 No Throttle-By-Wire – The cable-driven throttle limits integration with modern tuning solutions, drive-by-wire pedal setups, and adaptive cruise control.
🔴 Severely Limited OBD1 Diagnostics – The OBD1 system in the non-VVT 1UZ-FE lacks the ability to provide detailed engine diagnostics, making troubleshooting and tuning much harder.
✅ In contrast, OBD2 systems (found in the VVT-i 1UZ, 2UZ, and 3UZ) provide more advanced data logging, fault codes, and support modern scanning tools.
For these reasons, continuing to modify and wire non-VVT 1UZ-FE engines is no longer a viable or responsible option. To ensure our customers get the best possible performance and reliability from their swap, we strongly recommend upgrading to a 1UZ-FE VVT-i, 2UZ, or 3UZ, which we continue to support with full wiring, programming, and standalone setup services.
Recommended Alternatives
If you’re looking for a reliable and supported Toyota UZ swap, we recommend:
✅ 1UZ-FE VVT-i (More tunable and better suited for modern swaps)
✅ 2UZ-FE (Great for swaps needing more torque and displacement)
✅ 3UZ-FE (High-performance option with advanced ECU support)
We fully support these engines with our wiring and programming services, including standalone setups, ECU tuning, and immobilizer removal.
What Our 1UZ-FE Auto Wiring Service Previously Included
Our automatic transmission wiring modification allowed the 1UZ-FE non-VVT engine to function as a standalone system while retaining OEM management. The goal was to make the engine swap as simple and plug-and-play as possible for any project.
Key Features of the Service
🔧 Complete Harness Rework
We fully deconstructed and reassembled each engine harness to create a neater, more streamlined system by:
✅ Removing unnecessary wiring (e.g., EGR for track builds)
✅ Integrating a fuse box for power distribution
✅ Wiring the body-to-ECU connectors directly into the harness
🔧 Client Plug for Easy Vehicle Integration
We included a client plug pigtail, making it simple to connect the harness to the vehicle. This plug featured:
- Main Engine Start Wires: Ignition, crank signal, and fuel pump power supply
- Dashboard Outputs: Oil light, temperature gauge, charge light, and rev counter
- Automatic Transmission Signals (Separate Plug):
- Park, Reverse, Neutral, Drive, Overdrive, 2, and L
- These could be used for dash lights, reverse signals, and overdrive switches
🔧 Harness Cleanup & Protection
Each harness was fully inspected and reconditioned:
✅ Brittle split tubing replaced
✅ Wrapped in high-quality fabric tape for protection and longevity
🔧 Testing & Documentation
Every completed harness was tested on one of our shop test engines before shipping. Customers received:
✅ A test-run video showing the harness in action
✅ Detailed pictures of the final harness
✅ A shared folder containing:
- Welcome Pack
- Client Plug Pinouts
- Shipping details
- Invoice and any additional documentation
Parts Required for the Service
To complete the wiring modifications, we required customers to send:
✔️ Their engine harness and ECU
✔️ (Optional) Front harness section (supports crank/cam sensors, starter solenoid, knock sensors – often brittle and needing repair)
Previous Turnaround Time & Pricing
Turnaround time depended on the queue at our shop and typically ranged from 1 to 4 weeks.
💰 Previous Pricing:
- LS400 Wiring Modification: $590
- SC400 Wiring Modification: $690 (SC400 harnesses required more extensive reconstruction)
- Automatic Transmission Wiring Add-on: +$70
- Connector Replacements: Priced separately, averaging $6 each installed
Each harness varied in condition—some required minimal connector replacements, while others needed a full rework. We charged based on actual replacement needs.
Final Notes on Discontinuation
While we no longer offer this service, we continue to support wiring and programming for the 1UZ VVT-i, 2UZ-FE, and 3UZ-FE. These engines provide better ECU reliability, tuning flexibility, and easier integration into modern swaps.
If you’re considering an alternative UZ-series swap, feel free to contact us—we’re happy to guide you in the right direction!
Thank you to everyone who has trusted us with their 1UZ-FE automatic swaps over the years!
An example of what you will receive in video:
1UZ-FE OEM ECU Reliability
We would like to inform you that the service for modifying 1UZ non-VVT engine harnesses is discontinued. This decision has been made due to the fact that the ECUs for these engines often require a rebuild, which can lead to unforeseen expenses for the customer. We do not offer computer rebuilding services, and unfortunately, ECU rebuilders cannot guarantee that your rebuilt ECU will function as expected.
As an alternative, we recommend opting for aftermarket engine management for non-VVT 1UZ engines. This approach eliminates the risk of unexpected costs and provides you with a programmable ECU. It’s important to note that the OEM non-VVT 1UZ ECUs have read-only memory and cannot be modified. This makes aftermarket solutions a more flexible and reliable choice for managing your engine’s performance.
Additional Information
The Toyota 1UZ-FE 4.0L Engine: Specifications and Reliability
The 1UZ-FE, the first in the UZ engine series, was a 4.0-liter V8 gasoline engine featured in Toyota and Lexus luxury and sports cars from 1989 to 2002, before being replaced by the 3UZ-FE engine. It succeeded Toyota's older V family engines, which were used from the 1960s through the 1990s. The 1UZ-FE engine is characterized by an aluminum cylinder block with thin cast-iron cylinder liners and a 90-degree angle between the cylinder banks, offset by 21 mm. It features six main bearings and a forged steel crankshaft with eight counterweights. To minimize rotational mass, it includes lightweight forged steel connecting rods, aluminum pistons, and induction-hardened connecting rod pins. In late 1994, the 1UZ-FE received updates such as a lighter crankshaft, connecting rods, shorter piston pins, and redesigned pistons. Its quiet and smooth operation is largely due to liquid-filled compound engine mounts. In 1997, it was further refined with a more rigid cylinder block to enhance quietness.
The 1UZ engine is engineered more like a racing powerhouse than your typical road car engine. It's equipped with an eight counterweight crankshaft, and its components are designed to be lightweight. The bore and stroke dimensions are almost perfectly square, which is quite unique. But the standout feature has to be the DOHC 32-valve aluminum cylinder heads. This is a stark contrast to the older V8 engines, which usually had a single camshaft in the cylinder block and OHV heads with just two valves per cylinder. The 1UZ-FE, on the other hand, features two camshafts per head—one for intake and one for exhaust, with four valves for each cylinder. The intake camshafts are belt-driven, while the exhaust camshafts are gear-driven by the intake ones. Instead of using hydraulic lifters, this engine uses solid aluminum alloy valve lifters and steel outer shim type valve adjusters. Initially, the valve stem diameter was 6.0 mm for both intake and exhaust valves, with the intake valves being 33.5 mm in diameter and the exhaust valves 28.0 mm. But in a late 1997 update, the valve diameters were increased to 34.5 mm for intake and 29.0 mm for exhaust, and the stem diameter was reduced to 5.5 mm.
The initial design of the 1UZ-FE engine showcased a simple ignition system, comprising two distributors along with two ignition coils. This engine initially employed multi-port fuel injection (MFI) technology until 1994, which was then upgraded to sequential multiport fuel injection (SFI). The Non-VVT-i variant came with a mechanical throttle body and was fitted with an aluminum intake manifold. Additionally, it featured an Exhaust Gas Recirculation (EGR) system, which was responsible for redirecting a portion of the exhaust gases back into the combustion chambers. These gases were cooled by the engine's coolant system located at the rear before re-entry. However, the EGR system was phased out in 1997. As for the exhaust configuration, it boasted stainless steel headers and monolithic-type three-way catalytic converters.
Engine Specifications:
- Manufacturer: Tahara plant
- Production Years: 1989-2002
- Cylinder Block Material: Aluminum
- Cylinder Head Material: Aluminum
- Fuel Type: Gasoline
- Fuel System: Fuel injection
- Configuration: V
- Number of Cylinders: 8
- Valves Per Cylinder: 4
- Valvetrain Layout: DOHC
- Bore: 87.5 mm (3.44 in)
- Stroke: 82.5 mm (3.25 in)
- Displacement: 3,968 cc (242.1 cu in)
- Engine Type: Four-stroke, naturally aspirated
- Compression Ratios:
- 10.0:1
- 10.4:1 (since late 1994)
- 10.5:1 (since 1997 for VVT-i engines)
- Power Output:
- 251-261 hp (191-195 kW) at 5,400 rpm (non VVT-i)
- 290-300 hp (216-224 kW) at 5,900-6,000 rpm (with VVT-i)
- Torque:
- 260-269 lb-ft (353-365 Nm) at 4,400 rpm (non VVT-i)
- 300-310 lb-ft (407-420 Nm) at 4,000-4,100 rpm (with VVT-i)
- Engine Weight: 364 lbs (165 kg)
- Firing Order: 1-8-4-3-6-5-7-2
- Engine Oil Weight: 5W-30
- Engine Oil Capacity:
- 5.0 liters (0.3 for oil filter) for 1989-1994 models
- 5.1 liters (0.3 for oil filter) for 1994+ models
- Oil Change Interval:
- 6,000 miles (10,000 km) or 12 months for 1989-1994 models
- 9,000 miles (15,000 km) or 12 months for 1994+ models
- Applications: Lexus GS 400, Lexus LS 400, Lexus SC 400, Toyota Aristo, Toyota Celsior, Toyota Crown, Toyota Soarer
Lexus V8 Enignes LLC
Welcome! Website is still under construction and will be updated daily. Checkout has been disabled for now. If you would like to order it can be done via email at sales@lexusv8.com